Turn rotors when replacing pads?

My car informed me that the brake pads are in need of replacing. After a quick visual inspection the back pads look pretty much new, but the front ones are a bit worn. I haven't done an exact measurement but they look to be in the 3mm range which means its time to replace them. Luckily - the front rotors look practically new - there is no outer lip that can be seen or felt and when I run my fingernail across them it doesn't snag anywhere. I did a quick measurement with a caliper and they're 34mm - which according to the service manual is the width of a brand new front rotor. So, that brings me to the question - do you guys always have your rotors turned when replacing pads? In the past, I've just replaced the rotors with the pads - but since these are a bit more expensive than my previous cars + they appear to be more or less new, I'm not going to pitch them. Thanks in advance Charlie

I never turn them unless they're warped even with a big lip and have never had any problems. My wife and kids have always driven Mercedes and they recommend never turning the rotors, replace them if they're warped. Dan

i would just change the pads but i would take it easy until they bed-in 200 miles

Pretty much the only ones that will insist that you need to turn the rotor are those that profit by turning rotors. Bedding in Procedure: Or:

Assuming replacement pads are the same as the ones they are replacing no need to turn the rotors. If you switch pad types some manufacturer's instructions include turning the rotors.

You'll find that most European makes never machine their rotors, most Japanese always do. American cars used to be in the machining camp, now many are not. Different horses for different courses. I'm not sure I'd want to attempt to turn a set of drilled or slotted rotors anyway.

You can turn drilled rotors I had one done at O'Reilly

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Mechanic buddy from h.s. once told me American cars (c. 2000) weren't set up with pads & rotors that wear each other down, so the rotors needed to be turned to reset them. German cars have pads that wear down the rotors in addition to the rotors, so they need replacement more.

If your rotors need turning you might as well replace them , by the time you turn them you've spent 3/4 of the money you would need for new ones Usually you can just change pads before your rotors get to that point .

I would leave the rotors as they are and the testing station who does your annual will measure them and tell you when they are very near or fail them during the test. That's the time I would change the ones that are near or below the limit to pass the test. Other than that, change the pads and drive your car. nTake it easy until the pads bed in some.

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Your annual inspection pulls the wheels and measures the pads & rotors?!? Wow.... Here in Texas they drive the car in the station's parking lot. If it stops and the parking brakes hold, you're good to go. Honk the horn, make sure the wiper blades aren't brittle and that the lights work, plug in the OBD port, and you're done in 15 mins.

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depends on the rotors. It cost around $15 to have one turned. Yes, I get new rotors for around $80/pair. The one I had turned was virtually brand new, I installed a brake pad backwards (yes, I'm a dumbass) and it lightly scored the rotor before I figured it out. That was $15 well spent

if the new rotor is 34mm, and you have a set of completely worn pads. I cant believe the rotors are still 34mm. But thats just me. I always want to see shiny smooth rotors. I block sand them and polish them myself. Unless it gets to the point of turning them. So i would say to remeasure at different points, and have them turned if you have everything apart

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Here in CA, the state doesn't give a crap about safety of the car. There is zero safety inspection. Just a so-called smog inspection. But, in reality, that is a misnomer. They check emissions, and even if you pass the readings, if a component doesn't have a state-approved stamp imprinted on it, you fail.

Turnend rotors are not virtually brand new if they had heat spots of were warped. in those instances all turning does it makes it flat for a little while but since the metal is different in the heat spots or when it warps, the pulsation will come back. I only replace the rotors if they are warped, otherwise I just put on new pads and keep motoring. If the rotors are too thin for your driving style they will warp and you'll know there is a problem.

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Sort of. As is all too common, Hurdi is misinformed. They pull a front and a rear wheel and check the pads visually. If the pads are below a certain spec they fail. The spec is really easy to pass. It effectively is no different than whether the car still stops. At no point do they measure the rotor as part of the annual state inspection although a shop very well may do that as part of a comprehensive vehicle inspection.

Oklahoma discontinued their inspection requirement a few years back. So we just don't have to mess with inspections anymore. It's very convenient, especially for my catless x-pipe, but I'm not sure I agree with it.

Dumbass comment alert: I don't get this thread about "turn your rotors...", don't they TURN by themselves when the wheel moves?

Nice. On our Expedition, the front caliper was stuck and brake pads went to metal roughing up the rotor pretty bad. But it was still within thickness tolerances so I just had the shop put on a new set of $30 brake pads with lifetime warranty and called it good. Obviously a lot of shops wouldn't do this but this one would. The car stops strong and evenly, there's no excessive wear on the pads, and 10k miles later the rotors have smoothed themselves out.

"Turning rotors" is when you take them to a hardware store or auto repair shop. A diamond or carbide tool is used with a rotor lathe to machine off any defects to make the stopping surface as flat as possible. If you're using drilled rotors, examine the rotors carefully before determining whether to reuse the rotors for another set of pads. Minor crazing around individual holes isn't necessarily time to chuck the rotor, but I would not attempt to resurface ("turn") a rotor with ANY stress cracking. Any cracks that extend between drill holes are grounds for rotor replacement in my book. Any cracks that extend from a drilled hole to the outside edge of the rotor are cause for IMMEDIATE replacement. Do some Googling to see what happens when brake rotors frag. Some shops will not turn drilled or slotted rotors. Others say drilled rotors are no problem. At brake pad replacement time, measure rotor thickness and check for cracks. Replace if under spec or any significant cracking, and follow any info in the service manual. I use a straight edge to gauge whether the rotor is wearing evenly. If it is, I reuse it as long as it's within spec. If a face is wearing unevenly, it's time to chuck the rotor and inspect or repair the caliper responsible for the uneven wear. If you see a deep gash/groove in the rotor surface, figure out why that's happening and fix it. The rotor should be resurfaced with enough material removed to completely eliminate the groove, and THEN be checked with a caliper to ensure the resurfaced rotor is still within spec. If you are using aftermarket rotors, verify with the manufacturer whether they recommend resurfacing or replacement.

Thank you guys. Curious, is it more cost effective to have this procedure done, or would replacement for your average rotor make better sense? Would they repair high end rotors like the ceramic type? As a side non-porsche note... I had Volvo put brand new rotors and pads on my S60. One trip to the mountains and the car started shaking worse than a washing machine off balance. Volvo said the rotors were damaged from uneven wear. They replaced them at no charge. I love Volvo!

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Depends on a bunch of variables, most important is replacement cost and remaining thickness. For my Miata, it is never better to turn them ($22/per for new) but for a 996 it might be.

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That's just false, like the ***** on a slakker "girlfriend."

bwhahahaha.... NICE!!! hahahahaha

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If your rotors are well above the minimum thickness, and you have no issues with brake vibration, there is zero reason to replace or resurface those rotors. Just replace the pads, and go through an appropriate bedding-in procedure to mate the new pads to your old rotors. As others have said, rotors for most cars are so cheap that in general resurfacing just doesn't make much financial sense. You're cutting away a decent amount of the thickness of the rotor when turning it, so you're wasting some of its usable life, and also there's the chance the technician botches the job and you end up with vibration issues anyway. Better to just spend the money on known good new parts. Sounds like your rotors are perfect, so just keep using them until you have a problem or they are worn out!

i am shocked we have yet to hear a 400 word plus reply by you know who [although we did get close]............i wag page 3 and he splains it to yall

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Schnellster just needs 111 more words.....

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It's coming, I'm sure of it. I have a hunch that there will be a three-installment series: Volume 1: Brake system basics Volume 2: Replace or Resurface? Volume 3: Why you should NEVER read volume 2!

Ceramic rotors cannot be resurfaced - at least not as far as I know. PCCB sounds tempting, but the number of Internet tales about rotors getting chipped and otherwise destroyed (and the replacement costs) makes the iron ones seem even more attractive.

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That would have to be Macster, right? hahaha!

Wow thanks for all the useful information. I honestly would have guessed having them turned is par for the course - but I'm glad to hear that isn't. That will save me some time and effort. Regarding the turn vs. replace argument - when the cost is similar, replacing makes sense, but I try to stay with genuine parts when possible and a new set of front rotors is > $400. So, paying $40 to have them turned would be a big savings. Regarding my 34mm measurement - that was taken reaching through the spokes of the wheel and may be off my 1mm or so. I'll measure them properly once I remove the wheels. From the looks of it - the previous owner had replaced rotors and pads all the way around shortly before trading the car in. It also seemed like had replaced the clutch at some point - but I trashed it and got a new one 'while I was in there'. Cheers Charlie

The flagrant cheater's version of a dial caliper, of course, is "does my fingernail catch on the lip of the rotor, and if so, how much?" Has anyone tried the Pagid rotors? I've always used Zimmerman in the past, but at $63 each, damn.

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IIRC, the difference between new and worn out is 2mm, so if you are off by 1mm or so, that is HUGE!

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Yeah, but the PCCBs cut down my commute time to Cars n' Coffee by 4 seconds each way, so . . .

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Fair enough, but you can get Zimmermann rotors for half that price or Meyle for 1/4th. When you get down in that range, spending $100 on a decent set of rotors with 100% life remaining looks pretty good compared to spending $40 and a bunch of time to have somebody possibly screw your car up, and at best have 50% rotor life remaining.